The present invention relates generally to target-aerosal discrimination by means of digital signal processing, in Particular for optical (laser) proximity sensors at short range.
Active optical proximity sensors are considered to be advantageous over radio frequency counterparts for proximity fuzing in terms of its range and azimuthal resolution, and susceptibility to countermeasures. However, the presence of dense clouds, fog, or snow will create false signals and will obscure proper detection of the target. Efforts to develop a robust all-weather optical sensor have not been successful heretofore.
Patents of interest include U.S. Pat. No. 4,397,549, to Morgan, which teaches a method of the removal of LIDAR background backscattering by subtraction of multiple-delayed return signals. U.S. Pat. No. 4,742,353 to D'Addio et al teaches a digital processor for radar signals that suppresses clutter and enhances the target signal in a Doppler system. U.S. Pat. No. 4,881,077 to Jehle et al teaches a radar system which avoids rain echoes by employing a circularly polarized antenna. U.S. Pat. No. 4,884,440 teaches a method for eliminating noise from a data stream by measuring the noise and retrieving the part of the data stream uncontaminated by the noise. U.S. Pat. No. 4,937,583 to Poinsard teaches a method of filtering the carrier frequency, f.sub.0, to obtain filtered frequencies f.sub.1 and f.sub.2 which are used to provide range and velocity data.